Phil Evans is an Infrastructure Optimisation consultant with Microsoft Services in the UK. He is a passionate believer in right-size computing and helps organisations get the best out of their IT infrastructure spend.

Phil uses a simple concept of equating IT equipment to electric space heaters running 24 x 7 in a refrigerator.

It's that simple, but few organisations are prepared to tackle poor utilisation of their server infrastructure. In the economic boom years, running an empty fridge was not a big deal. Today, however, it's different. Take Internet Service Providers - do they run servers that do little or nothing? I think not - they will provision new hardware when they absolutely have to and not before. Doing so is exactly how they steer a course between operating costs and profits.

The average server power supply runs at about 800 Watts peak capacity. That's having a home electric heater or vacuum cleaner on 24/7, producing lots of carbon. Now imagine the 300 vacuum cleaners being stored in a large fridge 24/7 and that's what you have in the average data center. It just doesn't add up.

Storage Area Networks (SANS)are even worse. These are intensively-packed units of hard disk drives that spin constantly, even when not in use. SAN units (aggregated into large collections) typically use 1500-2000 Watts EACH, meaning that the average implementation could use up to 40 Kilowatts of power - that's 40 electric fires (in a large fridge, don't forget) running 24/7.

Then consider the fridge itself. Would you put a heater in a fridge? Of course not - but that is exactly what a data center is and the only means of cooling for most installations is to chill air and push that air in. Doing so actually requires more energy than is actually being generated within the data center (simple laws of physics come into play here). Wouldn't it be better to just regulate the temperature of the incoming air into a data center rather than trying to isolate it from an energy perspective?

We take it for granted PUE is important, but many users don’t get it that data centers are like refrigerators full of space heaters. You can continue the story by saying a typical refrigerator cycles on and off and has a life cycle of 14 years, but imagine the stress put on the refrigerator as it runs 24 x 7 cooling the space heaters. The lifespan is now less than 5 years. Then you need battery backup and generators to keep your space heaters and refrigerators running when the power goes out.

Others may understand how their servers impact the data center infrastructure using this story. I am going to try this in a presentation.